The present invention is directed to thermoplastic compositions useful in laser sintering processes. More particularly, the present invention is directed to a thermoplastic composition comprising a block copolymer having a relatively high melting point, and, in preferred embodiments, a high heat of fusion.
Accordingly, one aspect of the present invention is to provide a thermoplastic composition that can be laser sintered to yield flexible articles of manufacture having excellent resolution, durability, and strength.
Another aspect of the present invention is to provide a laser sinterable thermoplastic composition comprising a mixture of (a) one or more particulate thermoplastic block copolymer having a melting point of about 180° C. to about 210° C., and, in preferred embodiments, a high heat of fusion (ΔHf), and (b) an optional particulate flow agent. In preferred embodiments, the block copolymer has a recrystallization temperature that is about 40° C. to about 60° C. below its melting point.
A block copolymer included in the present composition contains a multiplicity of recurring segments characterized as soft (amorphous) and hard (crystalline) segments. These segments are joined head to tail randomly to form the block copolymer. The soft segment is selected from the group consisting of ether and ester monomer units, and the hard segment is selected from the group consisting of ester, amide, and urethane monomer units.
Still another aspect of the present invention is to provide a method of manufacturing an article of manufacture using laser sintering comprising the steps of
(a) depositing a quantity of a thermoplastic composition of the present invention on a support surface;
(b) leveling the composition to form a smooth layer of the composition on the support surface;
(c) then directing an energy beam over a predetermined target area on the support surface causing the composition to form an integral layer; and
(d) repeating steps (a) to (c) to form additional layers that are integrally bonded to adjacent layers to form a three-dimensional article.
Yet another aspect of the present invention is to manufacture an article by a laser sintering process having a sufficient volume density such that an infiltration step to increase article density and strength can be omitted.
These and other novel aspects and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments taken in conjunction with the figures.